With the
present increase in the emission of greenhouse gasses, the [CO2] will double to app. 700 ppm and the average global
temperature will increase 4-5 °C by year 2075 (IPCC, 2013). For this changed
environment new crop cultivars and disease control strategies are demanded.

We
analyzed the effects in barley and oilseed rape from the future climate change.

In a
climate phytotron (RERAF, DTU-Risø) future climate scenarios were applied to
138 accessions of barley and 32 accessions of oilseed rape. Production
parameters were recorded in the different climate scenarios that represented
elevation of single abiotic factors - [CO2], [O3] and
temperature - and combinations of the abiotic factors. In a separate study it
was examined, how the climate scenarios are affecting resistance to the fungal
diseases spot blotch and powdery mildew. Production parameters and abundance of
diseases were also evaluated under field conditions in a Free Air
Carbon Enrichment facility.

Both for
barley and oilseed rape the seed yield was significantly reduced in treatments
with +5 ⁰C above ambient. When the [CO2] was
increased together with the temperature the yield deficit was reduced, but yield
was still lower than in the ambient treatment (barley -30 %, oilseed rape -10 %).
Large differences among accessions were recorded. Based on their environmental
stability (Si2 and Wi2) some of the
accessions could be identified as environmentally resilient, why they may serve
in the breeding of cultivars for tolerance to future environmental variation.
In an association mapping of the barley accessions, 118 SNP markers were found
to link to production parameters recorded in the 5 different environmental
treatments. When growing under elevated temperature or [O3],
infection by the biotrophic powdery mildew fungus decreased, whereas disease
symptoms and growth of the toxin secreting hemibiotrophic spot blotch fungus
increased compared to ambient conditions, implying that climate induced changes
in disease severity could be linked to the trophic lifestyle of the pathogens. Combination
of the climatic factors affected the diseases in an unpredictable non-additive
manner, emphasizing the importance of conducting multifactorial experiments,
when evaluating the potential effects of climate change. Enrich CO2
atmosphere in the field increased biomass and yield and decreased severity of
powdery mildew supporting the phytotron results.